Hydrogen peroxide bleaching of cellulose pulps obtained from brewer’s spent grain

Brewer’s spent grain (BSG) was evaluated for bleached pulp production. Two cellulose pulps with different chemical compositions were produced by soda pulping: one from the original raw material and the other from material pretreated by dilute acid. Both of them were bleached by a totally chlorine-free sequence performed in three stages, using 5% hydrogen peroxide in the two initial, and a 0.25 N NaOH solution in the last one. Chemical composition, kappa number, viscosity, brightness and yield of bleached and unbleached pulps were evaluated. The high hemicellulose (28.4% w/w) and extractives (5.8% w/w) contents in original BSG affected the pulping and bleaching processes. However, soda pulping of acid pretreated BSG gave a cellulose-rich pulp (90.4% w/w) with low hemicellulose and extractives contents (7.9% w/w and <3.4% w/w, respectively), which was easily bleached achieving a kappa number of 11.21, viscosity of 3.12 cp, brightness of 71.3%, cellulose content of 95.7% w/w, and residual lignin of 3.4% w/w. Alkaline and oxidative delignification of acid pretreated BSG was found as an attractive approach for producing high-purity, chlorine-free cellulose pulp.     

A novel application of microwave-assisted extraction of polyphenols from brewer’s spent grain with HPLC-DAD-MS analysis

This paper reports a novel application of microwave-assisted extraction (MAE) of polyphenols from brewer’s spent grains (BSG). A 2⁴ orthogonal composite design was used to obtain the optimal conditions of MAE. The influence of the MAE operational parameters (extraction time, temperature, solvent volume and stirring speed) on the extraction yield of ferulic acid was investigated through response surface methodology. The results showed that the optimal conditions were 15 min extraction time, 100 °C extraction temperature, 20 mL of solvent, and maximum stirring speed. Under these conditions, the yield of ferulic acid was 1.31 ± 0.04% (w/w), which was fivefold higher than that obtained with conventional solid–liquid extraction techniques. The developed new extraction method considerably reduces extraction time, energy and solvent consumption, while generating fewer wastes. HPLC-DAD-MS analysis indicated that other hydroxycinnamic acids and several ferulic acid dehydrodimers, as well as one dehydrotrimer were also present, confirming that BSG is a valuable source of antioxidant compounds.     

A cosolvent pretreatment: effect of solvent–water on enzymatic hydrolysis of glucan,lignin structure,and dynamics

Cellulose - In this study, a biomass pretreatment strategy with a recyclable cosolvent (toluene sulfonic acid/ethanol) was developed. The low boiling point solvent (78.15&nbsp;°C),...     

The synergetic effect of zinc phthalate and carboxymethyl cellulose–carbon nanotube of glass fibers surfaces on improving strength and toughness of polypropylene composite

The interfacial interaction between glass fibers (GFs) and polypropylene (PP) resin is the key factor which affects the properties of GFs reinforced PP composites. The β-transcrystallization (β-TC) structure induced by β-nucleating agent (β-NA) at the interface is beneficial to improving the interfacial performance and comprehensive mechanical properties. However, due to the poor adhesive ability, it is difficult to introduce β-NAs onto GFs surface directly. In this work, for solving above problem, the sodium carboxymethyl cellulose (CMC) and  NH₂ functionalized multiwalled carbon nanotubes (CNTs) were used to construct the network structure on GFs (CMC-CNT-GF) through plenty of active groups. Furthermore, the zinc phthalate (ZnPht, β-NA) was synthesized and coated on GFs surface by hydrogen bonds interaction with CMC-CNT and physical anchoring effect (ZnPht@CMC-CNT-GF). Finally, the hybrid GFs reinforced PP composite (iPP/ZnPht@CMC-CNT-GF) was prepared, which exhibited enhanced tensile, flexural, and impact strength by 20.1, 9.3, and 33.3%, respectively when compared with the iPP/raw GF due to the formation of β-TC and improvement of interfacial adhesion. This study provides an effective strategy to introduce β-NAs on GFs with network structure for improving interfacial properties by inducing β-TC to enhance the strength and toughness of composite, which could be applied in other fiber/semicrystalline polymer systems.     

The influence of the dialkylphenyltolane’s difluorosubstitution on mesomorphic and dielectric properties

The synthesis of variously difluoro-substituted 4-butyl-4?-[2-(4-butylphenyl)ethynyl]-1,1?-biphenyls is presented and discussed. Molecular correlations between positions of fluorine atoms at phenyltolane core and mesomorphic, dielectric properties of newly synthesised liquid crystals (LC) have been drawn and discussed. New LC molecules exhibit a wide range of nematic phase and are promising components of liquid crystalline mixtures. They were characterised by ¹H NMR spectroscopy and mass spectrometry analysis. Phase transition temperatures, enthalpies, mesomorphic and dielectric properties were confirmed by a polarising optical microscopy, differential scanning calorimetry and dielectric spectroscopy.     

The effect of ion-conducting spacers on mass transfer — numerical analysis and concentration field visualization by means of laser interferometry

Mathematical model is developed for the study of mass transfer processes under the laminar stationary flow in the channels of electromembrane system formed by alternating cation- and anion-exchange membranes at whose surfaces the ion-conducting spacers are fixed. The results of calculations are given of velocity and concentration fields, of current density distribution along the channel length for some values of Reynolds number and the values of the applied voltage. The comparison is made between the calculated mass transfer characteristics and the experimental data obtained by means of laser interferometry.     

The impact of measurement uncertainty on the producer’s and user’s risks, on classification and conformity assessment: an example based on tests on some construction products

The reliability of test results and subsequent classification statements or product certification depend on the variability of the product’s properties and on the validity of the test procedures used. With an emphasis on measurement uncertainty, producer’s and user’s risks as well as probabilities of conformance, conformity and classification are calculated exemplarily for two requirements for mineral aggregates used in construction. An important methodological basis is an international draft document on measurement uncertainty in conformity assessment. The mathematical instruments given are applied and further developed to a risk scenario for product classification. The results from a classification point of view show that the reliability of test results for acid-soluble sulphates is mostly acceptable and both the producer’s and user’s risks are quite small. In contrast, the magnesium sulphate index test produces results which are hardly usable for classification and certification purposes or for risk management in production. Product certification bodies should generally have an appropriate approach when dealing with results where precision data are poor.     

The archaeometry study of the chemical and mineral composition of pottery from Brazil’s Northeast

Chemical and mineralogical analysis was performed on ceramics and clay samples from Barracão archaeological site located in Baixo São Francisco River by means of instrumental neutron activation analysis (INAA) and by differential scanning calorimetry (DSC). The data set was studied by means of cluster analysis (CA) and discriminant analysis (DA). The results showed that the raw material used in ceramics is not local. By using DSC it was possible to discover that the principal minerals in the samples are quartz, feldspars, mica and kaolinite.     

The influence of precursor’s composition and concentration on cadmium doped TiO<Subscript>2</Subscript> film

The purpose of this article is to emphasize that new nanomaterials offer a number of attractive alternatives for solar energy use in wastewater photocatalysis. The wastewater from the textile industry contains dyes and heavy metals. Thin films of cadmium doped TiO₂ (Cd-TiO₂) were coated by a doctor blade using TiO₂ Degussa P25 and cadmium precursor (cadmium nitrate). The photocatalytic efficiency of cadmium doped TiO₂ is strongly influenced by crystal structure, particle size, particle morphology, porosity and doping. The pore size distribution and the roughness analysis have been studied by the atomic force microscopy (AFM) of the thin films. The photocatalytic activity of the samples was tested in Methyl orange and Methylene blue photodegradation. Cadmium doped TiO₂ catalyst does not significantly decrease the efficiency of photodegradation processes, and, in some situations, improves dye photodegradation.     

The effect of silane concentration on the adsorption of poly(vinyl acetate-co-maleate) and γ -methacryloxypropyl- trimethoxysilane onto E-glass fibers

The adsorption of a poly(vinyl acetate-co-maleate) (PVAM) emulsion onto E-glass fibers was investigated along with sizing formulations prepared by mixing the PVAM with varying concentrations of -methacryloxypropyltrimethoxysilane (MPS). The sized E-glass fibers were then characterized using Diffuse Reflectance Infrared Fourier Transform (DRIFT) spectroscopy, X-ray Photoelectron Spectroscopy (XPS) and Scanning Electron Microscopy (SEM). Loss on Ignition (LOI) along with the DRIFT spectra indicated that the addition of silane to the PVAM emulsion caused a decrease in the amount of size on the fiber. The decrease in amount of size on the E-glass fibers did not coincide with a decrease in surface coverage, instead the XPS results indicated surface coverage had increased with silane addition. These results showed that small increases in the silane concentration appear to affect the amount of size adsorbed to the E-glass fibers     

The effect of ‘crystallinity’ and structural disorder on the electrochemical performance of substituted nickel hydroxide electrodes

β_bc-Nickel hydroxide exhibit non-uniform broadening reflections in their PXRD pattern due to the presence of structural disorder. β_bc-Nickel hydroxide electrodes with smaller crystallite size and structural disorder reversibly exchanges 0.9e/Ni. Co/Zn/Ca/Cd-substituted β_bc-nickel hydroxide samples also display non-uniform broadening of reflections in their powder X-ray diffraction patterns with smaller crystallite size and exchanges 0.7–0.8e/Ni. Hydrothermal treatment of β_bc-nickel hydroxide slurry at 170 °C results in an ordering of reflections in their powder X-ray diffraction pattern with an increased crystallite size. Crystalline β-nickel hydroxide electrode reversibly exchanges 0.3–0.4e/Ni. Hydrothermal-treated Co/Zn/Ca/Cd-substituted β_bc-nickel hydroxide slurries at 170 °C display sharp reflections with similar crystallite size and electrochemical activities as that of crystalline β-nickel hydroxide. This clearly demonstrates that partial substitution of Co/Zn/Ca/Cd in the nickel hydroxide matrix does not show any dramatic improvement in their electrochemical activity at 25–30 °C. Structural disordered material with smaller crystallite size delivers electrochemical activity close to theoretical capacity.     

The effect of dopant’s valence (+III and +V) on the anion/cation uptake properties of antimony-doped tin dioxide

Antimony is perhaps the most frequently used doping element of tin dioxide. Although antimony of different oxidation states have been used in the synthesis, the effect of dopant’s valence on ion exchange properties has not been investigated critically. In our study the valence of antimony had clear effects on the metal uptake properties of Sb-doped SnO₂ materials. Extremely high Tc uptake (Kd > 100 000 mL g⁻¹) on Sb(III)-doped material was observed in conditions under which Sb(V)-doped material did not show any Tc uptake. However, the Sb(V)-doped material showed good Ni²⁺ uptake properties (Kd up to 33 000 mL g⁻¹), even at pH values below the material’s point of zero charge (pzc), while the Sb(III)-doped material showed Ni²⁺ uptake only at pH above its pzc. The cation uptake of Sb-doped SnO₂ resembles typical weakly acidic cation exchanger character but the uptake of TcO₄- does not follow a typical anion exchange pattern. Instead, we propose a sorption process related to redox reactions as the probable Tc uptake process.     

The effect of terminal alkoxy chain on mesophase behaviour,optical property and structure of chiral liquid crystal compounds derived from (−)-menthol

Herein, we present the results of our extensive investigations on the synthesis and phase behaviour of nine novel (?)-menthol-based chiral liquid crystal compounds. They possess three phenyl rings and substituted with (?)-menthyl and varying length of n-alkoxy chains at one end. With the aim of exploring the fundamental relationships between molecular structural features and thermal properties, nine terminal n-alkoxy groups from ethoxy to n-octadecaneloxy group in even numbers have been used. A detailed characterisation of their properties was carried out. The characterisation results clearly illustrate that all the series compounds show the thermodynamically stable phases; the shorter chain homologues display only the BPI and N* phases, and the middle ones exhibit BPI, N* and S_A* phases while the longer chain members show the BPI, N* and S_C* phases. Besides, the BPI appeared in a narrow temperature range because of their thermodynamic disruption. Temperature range of the N* phase narrows when the length of the n-alkoxy tail increases. The reflection peak is shifted towards short wavelength region with increasing temperature due to the winding of the chiral nematic helix in the N* phase. Furthermore, their inherent reflection peak intensities of reflections were gradually weakened.     

Evaluation of solvents’ effect on solubility,intermolecular interaction energies and habit of ascorbic acid crystals

Solubility of active pharmaceutical ingredient (API) in solvents is very important for drug development and manufacturing. Solubility data may provide further information such as thermochemical properties and intermolecular interactions that may lead to a better understanding of the formation of API crystals. In this study, solubility of ascorbic acid was determined by gravimetric method in four different commonly used polar protic solvents: water, methanol, ethanol and 2-propanol. The solubility of ascorbic acid crystal was also predicted using Conductor-like Screening Model – Realistic Solvent (COSMO-RS) approach. In this computational analysis, the generated ΔG values are based on the solubilities that were experimentally obtained to simulate the intermolecular forces. The intermolecular interaction data from COSMO-RS provide an insight into the relationship between the intermolecular interactions and its crystal habit across four different polar protic solvents. The habit of the crystals was then determined using light microscopy and scanning electron microscopy techniques, while the polymorphic form of the crystals was identified by X-ray powder diffraction and single X-ray diffraction techniques. The solubility and characterization data showed that the solvents with high polarity increased the solubility of ascorbic acid. The data also showed that different solvent polarity influenced the crystal habit, but did not change the crystal structure to form a new polymorph.     

The catalytic effect of acetate and its α-chloroderivatives on the acid hydrolysis of Cr(CN)(H2O)4NO+

The hydrolysis of Cr(CN)(H₂O₄)NO⁺ in carboxylate buffer solutions was studied. Acetate and its α-chloroderivatives catalyze the aquation reaction of the complex. The observed rate of the aquation of the CN ligand is the sum of the contributions of acid hydrolysis and the catalytic factor. The reactions are pseudo-first order with respect to the Cr complex. The catalytic contribution to the hydrolysis depends on the concentration of carboxylic acid anion and of H⁺ ions. The rate law also contains a term independent of the acid.The kinetic parameters of the catalyzed aquation were found and the reaction scheme proposed. The influence of carboxylate anions depends on their effect on the protonation equilibrium constant for the CN ligand and on the effect on the limiting rate of substitution of HCN and is explained in terms of ion-pair association. This mechanism is discussed and compared with other possible catalytic effects of anions on substitution reactions of the Cr(III) complexes.     

Catalyst-free synthesis of 1,2,4,5-tetrasubstituted imidazoles from arylamins,benzonitriles, arylglyoxals,and Meldrum’s acid

An efficient and catalyst-free for the synthesis of 1,2,4,5-tetrasubstituted imidazoles has been developed using a one-pot, two-step reaction of arylamins, benzonitriles, arylglyoxals, and Meldrum’s acid. All the products were obtained in good to excellent yields and their structures were established from their spectroscopic data.     

Chemical characterization,antioxidant properties and enzyme inhibition of Rutabaga root’s pulp and peel (Brassica napus L.)

Rutabaga (Brassica napus L.) belonging to Brassicaceae family, is a rich source of polyphenols and glucosinolates. Its consumption in human diet is highly appreciated for its nutritional contribution and health benefits. Brassica napus L. is recognized as the world's most widely grown temperate oilseed crop containing erucic acid for industrial applications, plants germination, animal feed and fuel. In this work we prepared two different extracts of Rutabaga root’s pulp and peel, e.g. ultrasound assisted extract (UAE) and homogenizer assisted extract (HAE). The four extracts have been analyzed by HPLC-MS to assess the phytochemical characterization and tested by antioxidant and enzyme inhibitor assays. Rutabaga pulp and peel extracts possess tyrosinase and glucosidase inhibitory activities together with a moderate antioxidant ability. Our results show a high level of glucosinolates, in particular neoglucobrassicin in the peel extract, which let us suppose a potential application as crop in industry and as supplement in human diet.